In the yeast Saccharomyces cerevisiae, the endoplasmic reticulum is found around the nucleus (perinuclear) and along the cell periphery (cortical ER). Although perinuclear ER appears to be connected to the cortical ER network, our findings suggest that these two types of ER may be delivered into daughter cells by different mechanisms. It is the long term goal of our studies to define the process by which cortical ER is delivered into daughter cells during the yeast cell cycle. This event must require a number of players such as a track for ER tubules to move into daughter cells. Other components would include a receptor for the ER in the daughter cell, machinery that retains the ER in the daughter cell, and factors that play a role in distributing the ER along the cell periphery. We have taken a genetic approach to identify the machinery that moves ER tubules from mother to daughter cells. This approach has resulted in the identification of four genes whose products are required for cortical ER inheritance (AUXI/SWA2, ICE2. ICE3 and ICE4). These genes encode products that appear to be involved in one or more of the events described above. We will characterize these components and identify additional players using a combination of genetic and biochemical approaches.